Non-Resident(External) Rupee Accounts (NRE Accounts): NRIs, PIOs, OCBs are eligible. These are rupee denominated accounts. Accounts can be in the form of savings, current, recurring or fixed deposit accounts. Accounts can be opened by remittance of funds in free foreign exchange. Foreign exchange brought in legally, repatriable incomes of the account holder, etc. can be credited to the account.

The deposits can be used for all legitimate purposes/ The balance in the account is freely repatriable.
There is no income tax or wealth tax on the deposits (except in the case of OCBs).
Joint operation with other NRIs/PIOs is permitted.
Power of attorney can be granted to residents for operation of accounts.

Ordinary Non-Resident Rupee Accounts (NRO Accounts)
These are Rupee denominated non-repatriable accounts and can be in the form of savings, current or term deposits. These accounts can be opened jointly with close relative in India, also. When an Indian National/PIO resident in India leaves for taking up employment, etc. outside the country, his bank account in India gets designated as NRO account.
The deposits can be used to make all legitimate payments in rupees.

Non-resident(Non-repatriable)Rupee Deposit Accounts (NRNR Accounts)
NRIs/PIOs/OCBs, other non-resident Individuals/entities are permitted to open these accounts. Accounts can be opened by transfer of freely convertible foreign currency funds from abroad, or from NRE/FCNR accounts. Deposits can be held jointly with a resident. Deposits can be for period from 6 months to 3 years, and can be renewed further.
The principal is non-repatriable; interest can be repatriated. There is no income tax on the interest (not available for residents)

Foreign Currency (Non-Resident) Accounts (Banks)(FCNR (B) Accounts)
NRIs/PIOs/OCBs are permitted to open such accounts in US Dollars, Sterling Pounds. Deutsche Marks and Japanese Yen, as term deposits (6 months to 3 years).